Graduated Neutral Density Filters
For landscape photographers the golden hours of light at the beginning and end of day are captivating. Long shadows and dynamic colors that illuminate the natural beauty at this time are certainly magical. Unfortunately, it may be impossible to capture what we see with one exposure because of the limitations in film and camera sensor technology. “Why not” is a good question? Our eyes have a variable aperture called a pupil, so when we view the highlight details (like the sky illuminated by the rising or setting sun) our pupils constrict. When we view the shadow details (like the landscape illuminated by only the sky) our pupils expand allowing us to see the details in both the highlights and shadows. The camera with only one aperture during an exposure doesn’t have this luxury. We can either expose for the highlights and allow the shadows to lose detail or visa versa.
Throughout photographic history various techniques have evolved to overcome this problem of high contrast and the inability of the camera to record details in both highlight and shadow. Merging two negatives when printing or processing more than one digital file in camera or software applications on the computer are two possible solutions. All techniques have their own particular nuances in getting acceptable results. There is only one option, however that can accomplish this with one exposure and a raw file format in camera and that’s the graduated neutral density filter (GND). This filter is used to partially block light in a portion of the scene (specifically the highlights), allowing us to expose for the shadows… thus minimizing the range of contrast and allowing the camera to record detail in both. It was a game changer in the 1990’s when the acclaimed adventure and landscape photographer, Galen Rowell, popularized the filters for the 35mm format with transparency film and their use is still prudent today shooting digitally. A series of these great filters are manufactured by Singh Ray and bear his name.
Like any tool we use to correct photographic deficiencies, there’s a fine line for achieving great results. Here’s a little info and a few tips to get you started down the right path when choosing and using your GND filters:
The rectangular style GND filters allow the gradient to be placed anywhere in the frame, accommodating nearly every situation. Cokin, Lee and Singh Ray are the most popular brands and they all fit the Cokin P system. The system holds up to 3 rectangular filters and mounts to your lens via an adapter, so you can work hands free. Cokin and Lee filters are made of plastic & resin respectably, which means less weight and cost at the expense of optical quality. Singh Ray filters are glass which means heavier, higher quality and pretty pricey at around $160 per filter. Be aware that various sizes are made. Make sure the filters, holder and adapters are compatible with your lens system.
Photos courtesy of Tim Cooper and B&H Photo
The filters come in various densities and the most common are 1, 2 or 3-stops with soft and hard gradients to accommodate various transitions in the landscape you’re confronted with. If your budget can’t include all the available filter combinations, I’d recommend getting the 1-stop hard and 2-top soft. You can use them together if you need 3 stops of density.
*Note: The circular style GND filter (pictured below) is nearly useless and a waste of money, because the gradient or transition is fixed in the middle and ultimately dictates where the composition will exist… “yikes”. If you have one, maybe use it as a coaster for your favorite beverage?
- Decide on a soft or hard edge (transition) to the gradient. The scene’s transition between highlight and shadow will dictate which one you choose… remember the goal is to blend it so it looks natural or close to how our eyes see the scene.
Be mindful of scenes where features such as trees, mountains, etc. exist in both the shadow and highlight. The filter will darken these elements as they ascend through the gradient and will be obvious to the viewer that a filter was used.
A better technique when you are confronted with this is through bracketing and using high dynamic range (HDR) software to blend the exposures together. RMSP instructor, Tim Cooper, wrote a blog article not so long ago that describes the HDR approach.
- Meter properly and choose the appropriate filter density.
Start with a good exposure reading for the highlights (usually the sky or clouds) and take note of the shutter speed. Your spot meter is perfect for this application.
Get an exposure reading for the shadows (usually the foreground) and make sure the exposure is a “darker” by a half to a full stop from normal. This is the exposure setting you’ll use when you take the picture with the filter. Once again take note of the shutter speed and compare it to the shutter speed reading when you metered for the highlights.
*Note: If your having trouble seeing where the filter is having an affect through the view finder, try stopping down to your smallest aperture for a moment and use the DOF preview button. The Live View mode is also great for evaluating the filters effect before you release the shutter.
The exposure is 1/4s with a 2 stop soft GND filter pulled down to the base of the mountains… awesome!
Don’t get discouraged if the first couple tries don’t work out so well. With a little practice you’ll soon be capturing that beautiful magic light that makes your landscape photos shine!
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